Laminated nonwoven fabric and method of manufacturing same

ABSTRACT

A laminated nonwoven fabric having a good texture, providing no rough touch, and having a high strength and a large delamination strength are provided. 
     A nonwoven fabric of a multi-layer structure comprises (a) a composite spun bonded nonwoven fabric composed of a low melting point resin component and a high melting point resin component and (b) a composite melt blown extra-fine-fiber nonwoven fabric having a fiber diameter of 10 μm or less and being composed of a low melting point resin and a high melting point resin; both of the nonwoven fabrics are laminated, and the fibers in each of the nonwoven fabrics and both of the nonwoven fabrics are thermally fused. 
     A method of manufacturing a nonwoven fabric having a multi-layer structure comprises laminating each of the nonwoven fabrics in a multi-layer structure and heating the laminate at a temperature higher than the thermal fusion temperature to cause thermal fusion of the both layers.

TECHNICAL FIELD

The present invention relates to a laminated nonwoven fabric and to amethod of manufacturing the same. More specifically, the presentinvention relates to a nonwoven fabric of multi-layer structurecomprising a composite spun bonded nonwoven fabric laminated on acomposite meltblown extra-fine-fiber nonwoven fabric. The laminatednonwoven fabric is preferably used as surface material for absorptiveproducts such as disposable diapers and sanitary napkins.

BACKGROUND ART

Spun bonded nonwoven fabrics have been used as surface material forabsorptive products such as disposable diapers, because they are hardlynapped or fluffed and have excellent fiber detachment resistance.However, continuous fibers (filaments or long fibers) that form the spunbonded nonwoven fabrics are difficult to make finer. Thus, the spunbonded nonwoven fabrics are difficult to provide a soft texture likethat of meltblown nonwoven fabrics composed of extra-fine fibers. Inaddition, the spun bonded nonwoven fabrics have another drawback in thatwhen their constituent fibers are made finer, more single fibers are cutshort and thus more fibers of a larger fineness are mixed, leading todeterioration in texture.

Laid-open Japanese Patent Publication No. Sho 54-134177 discloses ameltblown nonwoven fabric composed of extra-fine polypropylene fibers,and Laid-open Japanese Patent Publication Nos. Sho 62-299501 and Hei3-75056 disclose a disposable diaper employing a meltblown nonwovenfabric as its surface material. Meltblown nonwoven fabrics areadvantageous in that they provide a soft texture due to their smallfiber diameter. However, meltblown nonwoven fabrics have inherentdrawbacks, including weak nonwoven fabric strength, generation of napsor fluffs, and tendency of permitting fiber detachment. In addition,they have such drawbacks that polymer particles are likely to be formedat the time of spinning, thus imparting the fabrics rough hand feeling,and the fabrics irritate the skin, making it unsuitable for disposablediapers for newborn babies. In order to improve the strength ofmeltblown nonwoven fabrics and to prevent fiber detachment, themeltblown nonwoven fabrics are being subjected to pressing with heatedcalender rolls or heated emboss rolls. However, the heat pressing mustbe performed under severe temperature and pressure conditions, leadingto increase in the apparent density of the nonwoven fabrics anddeterioration in the texture thereof.

Japanese Patent Publication No. Sho 60-11148 and Laid-open JapanesePatent Publication Nos. Hei 2-112458 and Hei 2-234967 disclose alaminated nonwoven fabric wherein a spun bonded nonwoven fabric islaminated on a meltblown nonwoven fabric, and the two layers arethermally fused to each other by the use of heated calender rolls,heated emboss rolls, or the likes. The resultant nonwoven fabric hasimproved strength as compared with that of conventional single-layernonwoven fabrics. However, the nonwoven fabric has drawbacks, includingunsatisfactory fusion between layers, poor fiber detachment resistance,and insufficient delamination strength, since regular fibers are used ascontinuous fibers that compose the spun bonded nonwoven fabric. Inaddition, in order to press the spun bonded nonwoven fabrics with heatedemboss rolls, severe heating and pressing conditions are required,leading to drawbacks such as high apparent density and deterioration intexture.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a laminated nonwovenfabric which has a high strength, soft texture, and excellent fiberdetachment resistance, is not rough to the touch, and causes noirritation to the skin. Another object of the present invention is toprovide a method of manufacturing the laminated nonwoven fabric.

The present invention for achieving the above objects is summarized asfollows:

(1) A laminated nonwoven fabric of multi-layer structure comprising acomposite spun bonded nonwoven fabric laminated on a composite meltblownextra-fine-fiber nonwoven fabric having an average fiber diameter of 10μm or less; wherein

the composite spun bonded nonwoven fabric comprises a compositecontinuous fiber composed of a low melting point resin and a highmelting point resin, the difference in melting point between the lowmelting point resin and the high melting point resin being at least 10°C., the low melting point resin forming at least a portion of thesurface of the fiber, and the composite spun bonded nonwoven fabricbeing a partial thermal fusion product of the composite continuousfibers by the mediation of the low melting point resin,

the composite meltblown extra-fine-fiber nonwoven fabric comprisescomposite meltblown extra-fine fibers composed of a low melting pointresin and a high melting point resin, the difference in melting pointbetween the low melting point resin and the high melting point resinbeing at least 10° C., the low melting point resin forming at least aportion of the surface of the fiber, and the composite meltblownextra-fine-fiber nonwoven fabric being a partial thermal fusion productof the extra-fine fibers by the mediation of the low melting pointresin; and

the composite spun bonded nonwoven fabric and the composite melt-blownextra-fine-fiber nonwoven fabric are integrated by fusion of the lowmelting point resin of the composite spun bonded nonwoven fabric and/orthe low melting point resin of the composite meltblown extra-fine-fibernonwoven fabric.

(2) A laminated nonwoven fabric as described in (1), wherein

the composite spun bonded nonwoven fabric comprises composite continuousfibers having a fineness of 0.5-10 d/f,

the composite meltblown extra-fine-fiber nonwoven fabric comprisesextra-fine fibers having a fiber diameter of 0.1-10 μm, has 10/m² orless of polymer particles having a diameter of at least 0.1 mm, and hasan apparent density of 0.02-0.20 g/cm³; and

the laminated nonwoven fabric has a strength in the lateral direction of0.6 kg/5 cm or more, uniformity index of 0.6 or less, and a delaminationstrength between the two layers of 6 g/5 cm or more.

(3) An absorptive product comprising a laminated nonwoven fabric asdescribed in (1) or (2) as at least one component of the product.

(4) An absorptive product as described in (3) wherein the productcomprises a nonwoven fabric of double-layer structure composed of acomposite spun bonded nonwoven fabric and a composite meltblownextra-fine-fiber nonwoven fabric; or a nonwoven fabric of multi-layerstructure comprising at least three layers, composed of a composite spunbonded nonwoven fabric and a composite meltblown extra-fine-fibernonwoven fabric, and having the composite meltblown extra-fine-fibernonwoven fabric laminated on at least one side of the laminated nonwovenfabric.

(5) A method of manufacturing a laminated nonwoven fabric comprising thesteps of:

spinning composite continuous fibers from a low-melting point resin anda high melting point resin so that at least a portion of the fibersurface is formed by the low-melting point resin, the difference inmelting point between the low melting point resin and the high meltingpoint resin being at least 10° C., and forming a spun bonded web by acomposite spun bonding method; or heating the resultant fiber web at atemperature not lower than a thermal fusion temperature thereby to forma nonwoven fabric in which some parts of the fibers are thermally fused;

spinning composite meltblown extra-fine-fibers having an average fiberdiameter of 10 μm or less, and comprising a low-melting point resin anda high melting point resin, the difference in melting point between thelow melting point resin and the high melting point resin is at least 10°C., in such a fashion that the low-melting point resin forms at least aportion of the fiber surface, and forming a composite extra-fine-fiberweb which does not include thermally fused portions by self-heating atthe time of spinning, or forming a nonwoven fabric which includesportions thermally fused by self-heating at the time of spinning by acomposite melt-blowing method; or forming a composite extra-fine-fibernonwoven fabric in which some of the fibers are thermally fused byheating the spun fiber web or the nonwoven fabric which includesthermally self-fused portions at a temperature not lower than a thermalfusion temperature;

laminating the spun bonded web or the thermally fused nonwoven fabric,and the composite melt-blown extra-fine-fiber web or a compositemelt-blown extra-fine-fiber thermally-fused nonwoven fabric; and

heating the resultant laminate at a temperature not lower than thetemperature at which the two layers become thermally fused.

(6) A method of manufacturing a laminated nonwoven fabric as describedin (5) wherein the method further comprises a step of causingentanglement of the fibers in the webs or nonwoven fabrics of the twolayers by a needle-punch or spun lace means before or after heating.

(7) A method of manufacturing a laminated nonwoven fabric as describedin (6) wherein the laminate is heated with a through-air type heater atleast at a thermal fusion temperature of the two layers.

(8) A method of manufacturing a laminated nonwoven fabric as describedin (5) or (6) wherein the two layers are press-bonded under heating bythe use of emboss rolls having a thermal press-bonding area of 5-25%.

(9) A method of manufacturing a laminated nonwoven fabric as describedin (5) or (6) wherein the composite spun-bonded nonwoven fabric and thecomposite melt-blown extra-fine-fiber nonwoven fabric each having auniformity index of 0.6 or less are used as nonwoven fabric.

(10) A method of manufacturing a laminated nonwoven fabric as describedin (5) or (6) wherein the two layers are heated with an alternativelyhot-air jetting heater such that hot air is jetted from the top faceside and the bottom face side of the nonwoven fabric of multi-layerstructure in an alternating manner.

As the nonwoven fabric of multi-layer structure of the presentinvention, any fabric can be used so long as it is a nonwoven fabrichaving a structure of at least two layers in which a composite spunbonded nonwoven fabric and a composite meltblown extra-fine-fibernonwoven fabric are laminated. For application as wiping cloths orsurface material for disposable diapers, a nonwoven fabric having 2 or 3layers can be used, and for application as heat insulating material ormaterial for preventing moisture condensation, a nonwoven fabric having2 to 8 layers can be used.

The composite spun bonded nonwoven fabric used in the nonwoven fabrichaving a multi-layer structure of the present invention is produced fromat least two resin components having a difference in melting points byat least 10° C. by a composite spun bonding method and the fiberstherein are thermally fused to one another at the junctions thereof. Acomposite spun bonding method is a method of manufacturing a thermallyfused nonwoven fabric that comprises the following steps: A plurality ofresin components are melt extruded from a plurality of extruders. Theplurality of the resin components are extruded from a composite spinningnozzle to form continuous fibers such that a low melting point resincomponent forms at least a part of the fiber surface. The thus-obtainedfibers are aspirated by an airflow suction apparatus such as an airsucker, and then collected together with airflow by a web collectingapparatus such as a net conveyer. If necessary, the thus-obtained web issubjected to a treatment such as fusion by the use of a heatingapparatus using heated air or heating rolls.

There may be employed another method of manufacturing a nonwoven fabric,wherein spun continuous fibers are mechanically stretched, subsequentlyaspirated by an airflow suction apparatus such as an air sucker asmentioned above, then collected together with airflow by a webcollecting apparatus such as a net conveyer, and finally subjected tothermal fusion as in the case described above. In practice, two to fourresin components may be used as the resin components, and no limitationis imposed on the resin components so long as the difference between thehighest melting point and the lowest melting point of these resincomponents is at least 10° C. Use of two resin components is sufficientfor most applications.

The nonwoven fabric preferably has a uniformity index of basis weight,which will be described below, of 0.6 or less. Unification of basisweight can be achieved by selecting a composite spun-bonding machine orsetting the spinning conditions and the like by trial and error.

No limitation is imposed on the resins used in the present invention solong as they are spinnable thermoplastic resins. Examples of resins thatcan be used in the present invention include polyolefins such aspolypropylenes, high-density polyethylenes, mid-density polyethylenes,low-density polyethylenes, linear low-density polyethylenes, and binaryor ternary copolymers of propylene and another α-olefin; polyamides;polyesters such as polyethylene terephthalates, polybuteneterephthalates, low melting point polyesters obtained throughcopolymerization of a diol and terephthalic acid/isophthalic acid or thelikes, and polyester elastomers; fluorine plastics; mixtures of theresins described above; and other spinnable resins.

Examples of the combination of the resins at the time of compositespinning include high-density polyethylene/polypropylene, low-densitypolyethylene/propylene-ethylene-butene-1 crystalline copolymer,high-density polyethylene/polyethylene terephthalate, Nylon 6/Nylon 66,low melting point polyester/polyethylene terephthalate,polypropylene/polyethylene terephthalate, polyvinylidenefluoride/polyethylene terephthalate, and a mixture of linear low-densitypolyethylene and high-density polyethylene/polypropylene.

Examples of the form or morphology of the composite fibers includesheath-core, side-by-side, multi-layer, hollow multi-layer, andnot-circular multi-layer type. Also, it is sufficient that the lowmelting point resin component described above forms at least a part ofthe surface of the fibers. The difference in melting point between ahigh melting point resin and a low melting point resin is necessary tobe at least 10° C. When the difference is less than 10° C., (a) thetemperature is difficult to control when heat treatment is performedduring manufacture of the composite spun bonded nonwoven fabric or alaminated nonwoven fabric wherein the composite spun bonded nonwovenfabric is laminated on a composite meltblown extra-fine-fiber nonwovenfabric, or (b) thermal fusion is insufficient and thus a nonwoven fabrichaving a sufficient strength can not be obtained. Alternatively,wrinkles may be produced on the nonwoven fabric by heating at anexcessively high temperature and/or whole of the nonwoven fabric meltsto form a nonwoven fabric in which a portion of the fabric has afilm-like texture. Also, the thus-obtained laminated nonwoven fabric mayhave insufficient fiber detachment resistance or may readily be peeledoff at laminated surfaces.

The composite ratio of the low melting point resin to the high meltingpoint resin in the composite spun bonded continuous fibers is 10 to 90%by weight for the low-melting point resin and 90 to 10% by weigh for thehigh-melting point resin. More preferably, it is 30 to 70% by weight forthe low-melting point resin and 70 to 30% by weight for the high-meltingpoint resin. When the amount of the low melting point resin is less than10% by weight, thermal fusion of the composite spun bonded nonwovenfabric itself becomes insufficient or thermal fusion between thenonwoven fabric and the composite meltblown extra-fine-fiber nonwovenfabric at laminated surfaces becomes insufficient, thereby to produce anonwoven fabric of insufficient strength and insufficient fiberdetachment resistance.

The fineness of the composite continuous fibers is not particularlylimited. However, it is about 0.2 to 10 d/f in the case of the surfacematerial for disposable diapers, and about 0.5 to 20 d/f in the case ofwipers, and about 0.2 to 4000 d/f in the case of filters. While thebasis weight of the nonwoven fabric is not particularly limited, itfalls within the range of about 4-1000 g/m². In the case of the surfacematerial for disposable diapers, it is about 4 to 70 g/m²; in the caseof wipers or the likes, it is about 10 to 600 g/m²; and in the case offilters, it is about 20 to 1000 g/m².

Composite spun bonded nonwoven fabrics having a higher strength can beobtained by using a heater such as a air-through type heater, heatedcalender rolls, or heated embossing rolls. In the present invention, itis preferable to increase the strength of the nonwoven fabric alone toat least 0.6 kg/5 cm by using the aforementioned heater and controllingheating conditions and others.

The composite meltblown extra-fine-fiber nonwoven fabric used in thepresent invention is a nonwoven fabric obtained by the method asfollows: At least two thermoplastic resins whose melting points differfrom each other by at least 10° C. are separately melt extruded. Alow-melting point resin and a high-melting point resin are extruded froma composite-type melt blow spinning nozzle so that the low-melting pointresin forms at least a part of the fiber surface, and formed intostreams of extra-fine-fiber with a high temperature and high velocitygas by blow spinning, formed into a composite extra-fine-fiber web witha collecting apparatus, and subjected to a heat fusing treatment, whennecessary.

It is sufficient that a low-melting point resin forms at least a part ofthe fiber surface in the composite melt-blown extra-fine-fibers of thepresent invention. The composite ratio is preferably 10 to 90% by weightfor the low-melting point resin and 90 to 10% by weight for thehigh-melting point resin. It is sufficient that the form of compositefibers is sheath-core, side-by-side as in the case of spun bondingdescribed above.

As the resins, a variety of resins used for the aforementioned compositespun bonding can also be used. As the combination of resins, variouscombinations of resins as disclosed with reference to the composite spunbonding are possible. Examples of the combinations include high-densitypolyethylene/polypropylene, propylene-ethylene-butene-1 crystallinecopolymer, high-density polyethylene/polyethylene terephthalate, and lowmelting point polyester/polyethylene terephthalate.

As the gas used at the time of blow spinning, an inert gas such as airand nitrogen gas is usually used. The temperature of the gas is about200-500° C., preferably about 250-450° C., and the pressure is about0.1-6 kg/cm², preferably about 0.2-5.5 kg/cm². These spinning conditionscan suitably be selected according to the properties and combination ofthe resins to be used, intended fiber diameter, apparatuses includingspinning nozzles to be used, and the likes.

The nonwoven fabric is composed of composite extra-fine-fibers having anaverage fiber diameter of 10 μm or less. The average fiber diameter ispreferably 0.1-9 μm and more preferably 0.2-8 μm. When the fiberdiameter exceeds 10 μm, the texture of the web is deteriorated. However,the web having a fiber diameter of 0.1 μm or less is difficult tomanufacture and their price becomes expensive.

Meltblown nonwoven fabrics used in the present invention are thosewherein the number of polymer particles is 10/m² or less. The word“polymer particles” used herein means such ones as having a non-fibrousshape such as a round, oval, or tear-drop shape, and having a diameterof at least 0.1 mm. When the number of the polymer particles increases,the fabric has a rough texture and irritates the skin, even if thefabric feels soft to the touch. Therefore, such a fabric can not be usedas material that comes in direct contact with the skin, for instance, itcan not be used as a surface material for disposable diapers and asubstrate for cataplasm. Both surfaces of wiping cloths for eyeglasses,furniture, etc. are preferably made of meltblown nonwoven fabric.However, such wiping cloths may sometimes exhibit a disadvantage ofscratching furniture and the like in addition to the rough texturedescribed above.

In the present invention, the nonwoven fabrics having a uniformity indexof basis weight of 0.6 or less are preferably used. Such nonwovenfabrics can be obtained by selecting suitable spinning conditions forcomposite melt blow spinning and appropriate apparatuses.

The fibers of a composite meltblown extra-fine-fiber nonwoven fabricused in the present invention are thermally fused to one another at thejunctions thereof. The thermal fusion may be performed by self-heatingat the time of spinning, or by using a heater such as a heatedair-through type heater, heated calender rolls, or heated emboss rollsat a step after spinning. While the basis weight of the nonwoven fabricis not particularly limited, it is in the range of about 3-1000 g/m².The basis weight of the nonwoven fabric is about 3-60 g/m² in the caseof the surface material for disposable diapers, about 5-500 g/m² in thecase of wiping cloths, and about 15-1000 g/m² in the case of filters.The apparent density of the nonwoven fabrics is not particularlylimited, but preferably falls within the range of about 0.02-0.40 g/cm³from consideration of their texture.

The laminated nonwoven fabrics of the present invention can bemanufactured by laminating a composite spun bonded nonwoven fabric and acomposite meltblown nonwoven fabric described above, and then heatingthe laminated fabric by the use of a heater such as a heated through-airtype heater, an alternatively heated-air jetting type heater, heatedcalender rolls, heated emboss rolls, or a sonic bonding apparatus tocause thermal fusion of the two layers. When a heated through-air typeheater or an alternatively heated-air jetting type heater is used, thereis obtained a relatively bulky meltblown nonwoven fabric. When a heatedthrough-air type heater is used, the delamination strength between thelayers can be increased by heating the fabrics so that the heatpenetrates first from the side of the spun bonded nonwoven fabric, whichhas a relatively large fineness, to the side of the meltblown nonwovenfabric, which has a small fineness, since the heat is applied uniformlyto the fabrics. When the laminated nonwoven fabric is heated with athrough-air type heater with the side of the meltblown nonwoven fabricbeing faced to a heated air outlet of the heater, the delaminationstrength between the two layers can be controlled by selecting suitableheated air pressure, suction conditions, and others, since singlemeltblown extra-fine fibers come to be entangled in the spun bondednonwoven fabric layer and thermally fused twice within the spun bondednonwoven fabric and in the both layers. A bulky nonwoven fabric can alsobe obtained even when a heater which jets heated air alternately to thefront side and back side of the nonwoven fabric is used. A laminatednonwoven fabric having a high delamination strength can be obtained bylaminating both nonwoven fabrics, subjecting the laminated fabric to anentangling treatment, for example, by a needle punch method or a spunlace method, followed by a heating treatment. It is sufficient that theheating temperature is higher than the softening temperature of alow-melting point resin component of the composite continuous fibercomposing a composite spun bonded nonwoven fabric or higher than thesoftening temperature of the low-melting point resin of the compositemeltblown nonwoven fabric. When both of the two layers are heated,thermal fusion of fibers of either nonwoven fabric or both of thefabrics can also be performed at the same time. When a thermally fusedcomposite spun bonded nonwoven fabric is rolled, unrolled, and thenheated, it is sufficient that the heating temperature is higher than thesoftening temperature of the low-melting point resin of the meltblownnonwoven fabric. When it is heated at a temperature higher than thesoftening or thermal fusing temperature of the low-melting point resincomponent of the both composite spun bonded fabric and the meltblownnonwoven fabric, a laminated nonwoven fabric having a high delaminationstrength can be obtained. When it is heated with heated emboss rolls, itis preferable to make the area of heat pressing to 5-25%. When thethermal press-bonding area is less than 5%, detachment resistance andstrength of nonwoven fabric become poor. When the heat presing areaexceeds 25%, the texture of the thus-obtained fabric becomes hard.

In the present invention, it is preferable to make the delaminationstrength of the both layers higher than 6 g/5 cm by selecting properheating conditions, a low melting point resin of the composite spunbonded nonwoven fabric, a low melting point resin of the compositemeltblown extra-fine-fiber nonwoven fabric, and the likes. Thedelamination strength is 6-5000 g/5 cm, and more preferably about10-4000 g/5 cm. When the delamination strength is less than 6 g/5 cm,both of the layers are easily delaminated by friction, etc., thus makingthe laminated fabric unsuitable for disposable diapers or the likeproducts. When the same resin is used for both of the low-melting pointresin of the composite spun bonded nonwoven fabric and the low-meltingpoint resin of the composite meltblown extra-fine fiber, there can beobtained a laminated fabric of extremely high delamination strength.

Since the laminated nonwoven fabric of the present invention employs ahigh strength of a composite spun bonded nonwoven fabric, composite spunbonded nonwoven fabrics having a strength in the lateral direction of0.6 kg/5 cm or higher as reduced to that of a nonwoven fabric having abasis weight of 40 g/m² are preferable. The lateral direction usedherein refers to a so-called cross-machine direction (CD) of a spunbonded nonwoven fabric layer. When the laminated fabric hasmulti-layers, the strength in the lateral direction refers to the lesserof the longitudinal strength and the lateral strength. When the apparentdensity of laminated meltblown nonwoven fabrics after lamination isassumed to be 0.02-0.20 g/cm³, it is particularly preferred, because asoft texture of extra-fine-fibers of such a meltblown nonwoven fabriccan be employed for various uses, e.g. surface material for disposablediapers. The apparent density is about 0.02 to 0.20 g/cm³ in the casefor wiping cloths or surface material for disposable diapers, and0.025-0.40 g/cm³ in the case of filters or the like.

The laminated nonwoven fabrics of the present invention preferably has auniformity index of basis weight of 0.6 or less. Such nonwoven fabricscan be obtained by using a composite spun bonded nonwoven fabric and acomposite meltblown extra-fine-fiber nonwoven fabric each having auniformity index of basis weight of 0.6 or less.

The laminated nonwoven fabrics of the present invention can be used,singly or after being laminated with, sewed to, or thermally fused toanother material, for various uses. For instance, when the laminatednonwoven fabrics are used as a material for underpants-shaped disposablediapers, they can be used in areas where a relatively high waterrepellency is required; for example, as liner material used in thevicinity of the trunk and legs. When such diapers have a narrow strip ofa vertical blocking layer in the vicinity of the legs for prevention ofleakage of liquid, the laminated nonwoven fabric can also be used asmaterial for such vertical blocking layers after thermally fused toanother material. When the laminated nonwoven fabric is used in such adiaper, an elastic material can be used in combination with anothermaterial or the laminated nonwoven material so that the diapers arebrought into close contact with the trunk and the legs. Further, thelaminated nonwoven material can also be used as covering material for anunderpants-shaped disposable diapers with the layer of a compositemeltblown extra-fine-fiber nonwoven fabric being placed outside orinside. Still further, the laminated nonwoven fabric can also be used ascovering material for the aforementioned surface material and ascovering material for the liner material described above after laminatedon another nonwoven fabric, tissue, web, film, or the like.

The laminated nonwoven fabric can be used as a material for forming apart of the aforementioned surface material or liner material bydisposing a large number of permeation holes of about 0.1-9 mm² in anonwoven fabric of any one of the layers of a laminated nonwoven fabricsand/or the entire laminated nonwoven fabric so that liquid and moisturepermeate quickly. Further, the multi-layer nonwoven fabric may beapplied with a finishing agent (or oiling agent) such as a waterrepellent finishing agent and hydrophilic finishing agent, or afluorine-containing water repellent agent for controlling thepermeability.

The multi-layer nonwoven fabrics of the present invention can belaminated, for example, in such a sequence as meltblown nonwovenfabric/spun bonded nonwoven fabric/meltblown nonwoven fabric, appliedwith a variety of lubricants, and can be used for wipers for furnitureor the likes.

The laminated nonwoven fabrics may be processed into filtering materialafter being pleated, molded into a cylindrical (or tubular) shape,molded into a cylindrical shape by winding as they are; or molded into acylindrical shape while being heated so that the layers are thermallyfused to one another.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be described in more detail withreference to Examples. In the Examples, evaluation of nonwoven fabricswas carried out as follows:

Fiber diameter: Ten small pieces were cut away from a web or nonwovenfabric, a photograph of 100 to 5000 magnification was taken by using ascanning type electron microscope, and diameter of 100 sample fiberswere determined. Average value was assumed to be the fiber diameter(unit: μm).

Tensile strength of nonwoven fabric: Vertical breaking strength andlateral breaking strength (kg/5 cm) of a nonwoven fabric having a widthof 5 cm were determined by using a tensile strength tester. The averagevalue of five measurements was assumed to be the tensile strength.

Texture: Five panelists evaluated the texture (or hand feeling) of asample nonwoven fabric in terms of wrinkling, flexibility, and roughnessto the touch (rough feel). The judgment was made according to thefollowing standards. When three or more of the panelists judged that thesample had no wrinkling, had a high flexibility, and had no rough feel,the texture was decided to be “good,” and when three or more panelistsjudged that the sample had wrinkles, poor flexibility, or rough feeling,or any combination of two or more of these properties, the texture wasdecided to be “poor.”

Polymer particle: Ten sheets of nonwoven fabrics each having a size of20×20 cm were cut away at random, and the number of polymer particles(unit: number/m²) having a diameter larger than 0.1 mm were counted byusing a magnifying glass.

Fiber detachment: A sheet of nonwoven fabric having a size of 20×20 cmwas cut away and placed on a horizontal surface. A person in charge ofthe evaluation lightly press the surface of the nonwoven fabric with awet hand, and rub the surface of the fabric so as to draw a circlecontinuously five times. Subsequently, the person check the hand for thepresence or absence of detached fibers. When detached fibers werepresent on the hand, the fiber detachment was assumed to be “presence,”and when no detached fibers were present, the detachment was assumed tobe “absence.”

Delamination strength: A piece of laminated nonwoven fabric having awidth of 5 cm was cut away. One layer was peeled from the other layerwhile cutting fabric at the laminated surfaces by using a razor.Delamination strength was determined by the use of a tensile strengthtester. The average value of five measurements was assumed to be thedelamination strength (unit: g/5 cm).

Uniformity index of average basis weight of nonwoven fabric: 40 sampleshaving a size of 5 cm×5 cm were cut out from a laminated nonwoven fabricat random. The basis weight (g/m²) of each sample was measured. Theuniformity index of average basis weight was calculated from thefollowing formula.

Uniformity index=(maximum basis weight−minimum basis weight)/averagebasis weight.

EXAMPLE 1

A thermally fused composite nonwoven fabric was prepared by the use of acomposite-spun-bonding machine equipped with a composite spinningmachine, an air sucker, a net-conveyor, and a heater. Sheath-core typecomposite-spinning nozzles having an orifice diameter of 0.4 mm wereused. High-density polyethylene having a melting point of 133° C. and anMFR of 22 (190° C., g/10 minutes) was used on the sheath side as thefirst component, and polypropylene having a melting point of 164° C. andan MFR of 60 (230° C., g/10 minutes) was used on the core side as thesecond component. These polymers were spun at a composite ratio of 50/50(% by weight), a spinning temperature of 285° C. for the firstcomponent, and a spinning temperature of 300° C. for the secondcomponent, and then aspirated by the use of an air sucker at a velocityof 3000 m/minute. The resultant fibers were blown on the net-conveyortogether with air. The blown air was aspirated and removed by the use ofan aspirating exhaustion apparatus installed under the net-conveyor. Theresultant web had a fineness of 1.5 d/f. The web was heated at 145° C.by the use of a through-air type heater to obtain a nonwoven fabric inwhich the fibers were joined by thermal fusion. The nonwoven fabric hada basis weight of 18 g/m², uniformity index of 0.25, vertical strengthof 2.97 kg/5 cm, and lateral strength of 1.75 kg/5 cm.

A composite meltblown extra-fine-fiber nonwoven fabric was prepared bythe use of a melt-blow-spinning machine equipped with side-by-side typecomposite-melt-blow spinning nozzles having an orifice diameter of 0.3mm, a net conveyor, etc. Propylene-ethylene-butene-1 terpolymer having amelting point of 135° C. and an MFR of 76 (190° C., g/10 minutes) wasspun as the first component at a spinning temperature of 280° C., andpolypropylene having a melting point of 166° C. and an MFR of 82 (230°C., g/10 minutes) was spun as the second component at a spinningtemperature of 290° C. at a composite ratio of 50/50 (% by weight). Thespun fibers were blown to the net-conveyor by blowing heated air underconditions of air temperature of 360° C. and a pressure of 1.5 kg/cm².The blown air was aspirated and removed by the use of an aspiratingexhaustion apparatus installed under the net-conveyor. The resultant webhad a fiber diameter of 1.8 μm. The web was heated at 135° C. by the useof a through-air type heater to obtain a nonwoven fabric wherein fiberswere joined at junctions through thermal fusion of the low melting pointextra-fine fibers.

The nonwoven fabric had a basis weight of 20 g/m², uniformity index of0.14, vertical strength of 1.72 kg/5 cm, lateral strength of 0.89 kg/5cm, and apparent density of 0.055 g/cm³.

The composite spun bonded nonwoven fabric and the composite meltblownnonwoven fabric were laminated and heated at 142° C. by the use of athrough-air heater to obtain a laminated nonwoven fabric of two-layerstructure in which the two layers were thermally fused in part. The heattreatment was carried out in such a way that hot air was jetted from theside of the composite spun bonded fabric to the side of the compositemeltblown extra-fine fibers. The laminated nonwoven fabric slightlyincreased in its basis weight to 40 g/m² by the heat treatment performedafter lamination. The laminated nonwoven fabric had a uniformity indexof 0.18, vertical strength of 7.26 kg/5 cm, and lateral strength of 5.33kg/5 cm. Apparent density of the meltblown nonwoven fabric which wasseparated by cutting the laminated nonwoven fabric along the bondedsurfaces by the use of a razor slightly increased to 0.059 g/cm³ by theheat treatment after lamination.

The laminated nonwoven fabric had a good texture, no fiber detachment,no polymer particles, and a delamination strength of 149 g/5 cm.

EXAMPLE 2

A composite meltblown extra-fine-fiber nonwoven fabric was prepared bythe same preparation method as in Example 1. However, sheath-core type,composite-melt-blow spinning nozzles having an orifice diameter of 0.3mm were used. Treatment by the air-through type heater was not carriedout. Linear low density polyethylene having a melting point of 122° C.and an MFR of 122 (190° C., g/10 minutes) was spun as the firstcomponent at a spinning temperature of 260° C., and polypropylene havinga melting point of 165° C. and an MFR of 120 (230° C., g/10 minutes) wasspun as the second component at a composite ratio of the first componentto the second component of 40/60 (% by weight) and a spinningtemperature of 280° C., followed by blowing of heated air underconditions of heated air temperature of 370° C. and a pressure of 1.9kg/cm² to blow the spun fibers onto the net-conveyor. The resultant webhad a fiber diameter of 3.1 μm. The web had a structure like a nonwovenfabric having thermally fused portions at junctions of the fibers causedby the self-heating at the time of spinning. The resultant nonwovenfabric had a basis weight of 17 g/m², uniformity index of 0.30, verticalstrength of 0.86 kg/5 cm, lateral strength of 0.61 kg/5 cm, and apparentdensity of 0.043 g/cm³.

The composite spun bonded nonwoven fabric obtained in Example 1 and thecomposite meltblown nonwoven fabric described above which has thermallyfused portions caused by the self-heating, but was not subjected to aheat treatment were laminated and heated at 135° C., as in Example 1, toobtain a laminated nonwoven fabric of two-layer structure in which twolayers were thermally fused to each other. The heat treatment wascarried out with the composite meltblown nonwoven layer facing to theside from which heated air was jetted. Basis weight of the laminatednonwoven fabric was slightly increased to 36 g/m² by the heat treatment.The laminated nonwoven fabric had a uniformity index of 0.28, verticalstrength of 4.01 kg/5 cm, and lateral strength of 3.18 kg/5 cm. Apparentdensity of the meltblown nonwoven fabric which was determined aftercutting the laminated nonwoven fabric with a razor at the laminatedfaces to separate them was slightly increased to 0.046 g/cm³ by the heattreatment after lamination.

The laminated nonwoven fabric had a good texture, no fiber detachment,and no polymer particles, and its delamination strength was 102 g/5 cm.

COMPARATIVE EXAMPLE 1

A meltblown nonwoven fabric was prepared by the same preparation methodas in Example 1. However, heat treatment by the air-through type heaterafter spinning was not carried out. Melt-blow spinning nozzles forregular fiber having an orifice diameter of 0.3 mm were used.Polypropylene having a melting point of 167° C. and an MFR of 21 (230°C., g/10 minutes) was spun at a spinning temperature of 300° C.,followed by blowing of heated air under conditions of heated airtemperature of 360° C. and a pressure of 1.5 kg/cm² to obtain anextra-fine-fiber web. The resultant web had a fiber diameter of 8.9 μm.The web was a nonwoven fabric like product having thermally fusedportions at junctions of the fibers by the self-heating caused at thetime of spinning. The nonwoven fabric had a basis weight of 18 g/m². Thenonwoven fabric was found to have polymer particles by visual andtactile inspection. The nonwoven fabric had a uniformity index of 0.32,vertical strength of 0.88 kg/5 cm, lateral strength of 0.75 kg/5 cm, andapparent density of 0.070 g/cm³.

Polyethylene terephthalate spun bonded nonwoven fabric having a finenessof 2.6 d/f, basis weight of 20 g/m², uniformity index of 0.08, verticalstrength of 4.33 kg/5 cm, and lateral strength of 3.01 kg/5 cm and themeltblown nonwoven fabric described above were laminated and heated at158° C. as in Example 1 to obtain a laminated nonwoven fabric oftwo-layer structure in which the two layers were thermally fusedslightly. The spun bonded nonwoven fabric mentioned above was a productwhich was thermally fused in part by heated emboss rolls. The resultantlaminated nonwoven fabric slightly increased in basis weight to 40 g/m²by the heat treatment of the laminated product. The laminated nonwovenfabric had a uniformity index of 0.64, vertical strength of 6.85 kg/5cm, and lateral strength of 4.27 kg/5 cm. Apparent density of themeltblown nonwoven fabric which was determined after separating thelaminated faces was slightly increased to 0.084 g/cm³ by the heattreatment after lamination. In the laminated nonwoven fabric, wrinklesin the wave form were generated in the meltblown nonwoven fabric.

The laminated nonwoven fabric had no fiber detachment. The laminatednonwoven fabric was poor in flexibility, and had a rough texture andirritation to the skin due to the presence of polymer particles. Thefabric also had 26 polymer particles per square meter and a delaminationstrength of 5 g/5 cm.

COMPARATIVE EXAMPLE 2

A composite meltblown extra-fine-fiber nonwoven fabric was prepared bythe same preparation method as in Example 1. However, heat treatment wasnot carried out after spinning. The same resins as in Example 1 wereused as the first component and the second component, and the compositeratio of the components was also 50/50 (% by weight). Both the first andthe second components were spun at 250° C., followed by blowing heatedair under conditions of a heated air temperature of 250° C. and apressure of 0.8 kg/cm² to obtain an extra-fine-fiber web. The resultantweb had a fiber diameter of 18.9 μm. The web had a nonwoven fabric likestructure in which fibers were thermally fused at their junctions by theself-heating at the time of spinning. The nonwoven fabric had a basisweight of 16 g/m² and uniformity index of 0.13. The nonwoven fabric hada vertical strength of 0.91 kg/5 cm, lateral strength of 0.52 kg/5 cm,and apparent density of 0.065 g/cm³.

The composite spun bonded nonwoven fabric obtained in Example 1 and themeltblown nonwoven fabric described above were laminated and heated at140° C., as in Example 1, to obtain a laminated nonwoven fabric oftwo-layer structure in which the two layers were thermally fused inpart. The laminated nonwoven fabric slightly increased in basis weightto 35 g/m² by the heat treatment of the laminated product. The laminatednonwoven fabric had a uniformity index of 0.24, vertical strength of4.14 kg/5 cm, and lateral strength of 3.01 kg/5 cm. Apparent density ofthe meltblown nonwoven fabric determined after cutting the laminatednonwoven fabric at the laminated faces with a razor to separate wasslightly increased to 0.068 g/cm³ by the heat treatment afterlamination.

The laminated nonwoven fabric had no fiber detachment, no polymerparticles, and delamination strength of 61 g/5 cm. However, thelaminated nonwoven fabric had a hard, poor texture because the fiberswhich form the meltblown nonwoven fabric had a large fiber diameter.

EXAMPLE 3

A composite spun bonded nonwoven fabric was prepared by the samepreparation method as in Example 1. However, propylene-ethylene-butene-1terpolymer having a melting point of 135° C. and an MFR of 76 (230° C.,g/10 minutes) was used as the first component on the sheath side;polyethylene terephthalate having a melting point of 257° C. was used asthe second component on the core side; these polymers were spun underconditions of a composite ratio of 50/50 (% by weight), a spinningtemperature of 280° C. for the first component and a spinningtemperature of 295° C. for the second component; aspirated by an airsucker at a velocity of 2647 m/minute; and the resultant fibers wereblown onto a net-conveyor together with air. The resultant web had afineness of 1.7 d/f. The web was heated at 152° C. with a through-airtype heater to obtain a nonwoven fabric in which the fibers werethermally fused to each other in part. The nonwoven fabric had a basisweight of 23 g/m², uniformity index of 0.22, a vertical strength of 4.26kg/5 cm, and lateral strength of 3.81 kg/5 cm.

A composite meltblown extra-fine-fiber nonwoven fabric was prepared inthe same manner as in Example 1. However, heat treatment was not carriedout after spinning; sheath-core-type spinning nozzles having an orificediameter of 0.3 mm were used; the same terpolymer as used in Example 1was used as the first component on the sheath side and polypropylenehaving a melting point of 166° C. and an MFR of 74 (230° C., g/10minutes) was used as the second component on the core side; and thesepolymers were spun at a spinning temperature of 280° C. for both thefirst component and the second component wherein the composite ratio ofthe first component to the second component was 40/60 (% by weight); thetemperature of the heated air was 380° C., and the pressure was 2.3kg/cm². The resultant nonwoven fabric had a fiber diameter of 2.6 μm andbasis weight of 20 g/m². The nonwoven fabric was a product in whichfibers are weakly fused by the self-heating at the time of spinning. Thenonwoven fabric had a uniformity index of 0.34, vertical strength of0.54 kg/5 cm, lateral strength of 0.48 kg/5 cm, and apparent density of0.061 g/cm³.

The resultant composite spun bonded nonwoven fabric and compositemeltblown nonwoven fabric were laminated one on another and subjected toone step of a treatment for fiber entanglement with small columnar waterstreams by using a spun lacing apparatus under a condition of a pressureof 70 kg/cm². Then, the fabrics were heated at 150° C. as in Example 1to obtain a laminated nonwoven fabric of two-layer structure in whichtwo layers were thermally fused. The multi-layer nonwoven fabric wasslightly decreased in basis weight to 37 g/m² by the spun lacingtreatment or the heat treatment of the laminated product. The laminatednonwoven fabric had a uniformity index of 0.13, vertical strength of6.03 kg/5 cm, and lateral strength of 5.02 kg/5 cm. Apparent density ofthe meltblown nonwoven fabric determined after cutting the laminatednonwoven fabric at the laminated faces with a razor to separate them wasslightly increased to 0.092 g/cm³ by the spun lacing treatment afterlamination and heat treatment.

The laminated nonwoven fabric had a good texture and no fiberdetachment. The fabric had no polymer particles and a delaminationstrength of 405 g/5 cm.

EXAMPLE 4

The laminated nonwoven fabric of two-layer structure in which two layerswere thermally fused in part, and which was prepared in Example 2 waslaminated again such that the spun bonded nonwoven fabric layer formedthe inner side and the meltblown nonwoven fabric layer formed the outerside. Then, the laminated nonwoven fabric was heated at 145° C. by theuse of a heated air alternatively jetting type heater to obtain anonwoven fabric of four-layer structure in which the spun bondednonwoven fabrics were thermally fused to each other. The resultantlaminated nonwoven fabric had a basis weight of 74 g/m², uniformityindex of 0.28, vertical strength of 14.67 kg/5 cm, and lateral strengthof 11.32 kg/5 cm. The apparent density of the meltblown nonwoven fabricwas 0.052 g/cm³.

The laminated nonwoven fabric had a good texture and no fiberdetachment. The fabric had no polymer particles and a delaminationstrength of 204 g/5 cm. The laminated nonwoven fabric was able to usefor home-use wiping cloths as it was or after having being applied withone of a variety of lubricants by dipping or spraying method.

COMPARATIVE EXAMPLE 3

Polypropylene having a melting point of 165° C. and an MFR of 60 (230°C., g/10 minutes) was spun at a spinning temperature of 300° C. throughspun bond spinning nozzles, for regular fiber, having an orificediameter of 0.4 mm, the resultant fibers were aspirated by an air suckerat a velocity of 3000 m/minute and blown onto the net-conveyor togetherwith air. The blown air was aspirated and removed by the use of anaspirating exhaustion apparatus installed under the net-conveyor. Theresultant web was composed of regular fibers having a fineness of 1.5d/f. The web was heated at 162° C. with a through-air type heater toobtain a nonwoven fabric in which the fibers were thermally fused inpart. The nonwoven fabric had a basis weight of 18 g/m², uniformityindex of 0.75, vertical strength of 2.10 kg/5 cm, and lateral strengthof 1.35 kg/5 cm. The nonwoven fabric was heat-treated at a temperatureslightly lower than the melting point of the fiber. However, the fabrichad incomplete thermal fusion on one side thereof, and moreover, hadwrinkles generated therein because of heat shrinkage occurred at thetime of the heating.

A meltblown nonwoven fabric was prepared by the same preparation methodas in Example 1. However, heat treatment by the air-through type heaterafter spinning was not carried out; spinning nozzles, for regularfibers, having an orifice diameter of 0.3 mm were used; polypropylenehaving a melting point of 166° C. and an MFR of 74 (230° C., g/10minutes) was spun at a spinning temperature of 290° C., and heated airwas blown under conditions of a heated air temperature of 380° C. and apressure of 2.0 kg/cm² to obtain an extra-fine-fiber web. The resultantweb had a fiber diameter of 3.2 μm. The web was a nonwoven fabric likeproduct having thermally fused portions between fibers caused by theself-heating at the time of spinning. The nonwoven fabric had a basisweight of 18 g/m², uniformity index of 0.21, vertical strength of 0.72kg/5 cm, lateral strength of 0.60 kg/5 cm, and apparent density of 0.078g/cm³.

The spun bonded nonwoven fabric and the polypropylene meltblown nonwovenfabric both described above were laminated and heated at 162° C. by theuse of the through-air-type heater as in Example 1 to obtain a laminatednonwoven fabric of two-layer structure having a basis weight of 39 g/m²in which the two layers were thermally fused in part. The laminatednonwoven fabric had a uniformity index of 0.63, vertical strength of4.87 kg/5 cm, and lateral strength of 4.24 kg/5 cm. The nonwoven fabricwas heat-treated at a temperature slightly lower than the melting pointof polypropylene. However, the fabric had wrinkles therein because ofheat-shrinkage. Apparent density of the meltblown nonwoven fabricdetermined after cutting the laminated fabric at laminated faces with arazor to separate them increased to 0.081 g/cm³ by the heat treatmentafter lamination.

The laminated nonwoven fabric had no fiber detachment, no polymerparticles, and a delamination strength of 266 g/5 cm. The laminatednonwoven fabric had wrinkles therein and had a poor texture.

COMPARATIVE EXAMPLE 4

A meltblown nonwoven fabric was prepared by the same preparation methodas in Example 1. However, spinning nozzles, for regular fiber, having anorifice diameter of 0.3 mm were used; heat treatment with a through-airtype heater after spinning was not carried out; and polyethyleneterephthalate having a melting point of 257° C. was spun at a spinningtemperature of 300° C.; heated air was blown under conditions of aheated air temperature of 360° C. and a pressure of 1.8 kg/cm² to obtainan extra-fine-fiber web. The resultant web had an average fiber diameterof 5.2 μm. The web had little thermally fused portions between fiberscaused by the self-heating at the time of spinning. When the web waspressed by hand and then the hand was moved off the web, the fibersdetached from the web were present on whole surface of the hand. The webhad a uniformity index of 0.22, basis weight of 16 g/m², verticalstrength of 0.03 kg/5 cm, lateral strength of 0.01 kg/5 cm, and apparentparent density of 0.070 g/cm³.

The composite spun bonded nonwoven fabric obtained in Example 3 and themeltblown web described above were laminated and heated at 148° C. witha through-air type heater, as in Example 1, to obtain a laminatednonwoven fabric of two-layer structure in which the two layers werethermally fused in part. The nonwoven fabric had a basis weight of 39g/m², uniformity index of 0.25, vertical strength of 4.63 kg/5 cm, andlateral strength of 3.92 kg/5 cm. Apparent density of the meltblownnonwoven fabric determined after cutting the nonwoven fabric with arazor at laminated surfaces to separate them was 0.072 g/cm³. Thedelamination strength was 4.9 g/5 cm.

The laminated nonwoven fabric had a good texture and no polymerparticles. However, many fibers were detached from the web, and thus itwas judged to be bad in fiber detachment resistance.

EXAMPLE 5

The composite spun bonded nonwoven fabric obtained in Example 1 and thesheath-core type composite meltblown extra-fine-fiber nonwoven fabricobtained in Example 2 were laminated and pressed with heated embossrolls. As the rolls, a combination of a calendering roll and an embossroll in which the area of the convex portion is 15% of the whole areawas used, and the meltblown nonwoven fabric was arranged to contact withthe emboss roll. Conditions for pressing under heating were such thatthe temperature of the embossing rolls was 120° C., the temperature ofthe calender rolls was 120° C., and the linear pressure was 25 kg/cm.

The laminated nonwoven fabric had a uniformity index of 0.26 and a basisweight of 35 g/m². Apparent density of the composite meltblownextra-fine-fiber nonwoven fabric determined after cutting the nonwovenfabric with a razor at laminated surfaces to separate them was 0.11g/cm³. The laminated nonwoven fabric had a vertical strength of 8.92kg/5 cm, lateral strength of 7.65 kg/5 cm, and delamination strength of827 g/5 cm.

The laminated nonwoven fabric had a good texture, no polymer particles,and no fiber detachment.

EXAMPLE 6

A composite meltblown extra-fine-fiber nonwoven fabric was prepared bythe same preparation method as in Example 1. However, a high densitypolyethylene having a melting point of 135° C. and an MFR of 28 (190°C., g/10 minutes) was used as the first component and spun at a spinningtemperature of 280° C.; polypropylene having a melting point of 166° C.and an MFR of 36 (230° C., g/10 minutes) was used as the secondcomponent and spun at a spinning temperature of 260° C.; heated air wasblown under conditions of a heated air temperature of 340° C. and apressure of 2.1 kg/cm², and a side-by-side extra-fine composite fibernonwoven fabric having a composite ratio of 50/50 (% by weight) wasobtained. The resultant web had a fiber diameter of 7.6 μm. The web wasa nonwoven fabric like product having thermally fused portions betweenfibers caused by the self-heating at the time of spinning. Then, thenonwoven fabric was heated at 145° C. by using an air-through typeheater to obtain a nonwoven fabric having thermally fused portions. Theresultant nonwoven fabric had a basis weight of 20 g/m² and was found tohave few polymer particles by tactile inspection. The nonwoven fabrichad a uniformity index of 0.32, vertical strength of 1.77 kg/5 cm,lateral strength of 1.09 kg/5 cm, and apparent density of 0.046 g/cm³.

The composite spun bonded nonwoven fabric obtained in Example 1 and thecomposite meltblown nonwoven fabric described above were laminated andheated at 145° C. as in Example 1 to obtain a laminated nonwoven fabricof two-layer structure in which the two layers were thermally fused inpart. The laminated nonwoven fabric slightly increased in basis weightto 39 g/m² by the heat treatment of the laminated product. The laminatednonwoven fabric had a uniformity index of 0.26, vertical strength of5.03 kg/5 cm, and lateral strength of 4.16 kg/5 cm. Apparent density ofthe meltblown nonwoven fabric determined after cutting the laminatednonwoven fabric with a razor at laminated surfaces to separate them wasslightly increased to 0.051 g/cm³ by the heat treatment afterlamination. The laminated nonwoven fabric had a delamination strength of203 g/5 cm.

The laminated nonwoven fabric had no fiber detachment. The meltblownnonwoven fabric had 2.8 polymer particles per square meter. Thelaminated nonwoven fabric had a good flexibility, had a little roughfeeling due to the particles. The laminated nonwoven fabric can be usedfor thermal-insulation material and filtering material.

EXAMPLE 7

Using a commercial disposable diaper which had a shape of roughly I(cross-sectional shape of rail) when unfolded flat, only the topmaterial of the disposable diaper in the vicinity of the portions whichabut on the user's legs were replaced by the laminated nonwoven fabricobtained in Example 1.

The disposable diaper is composed of polyethylene/polypropylenethermally fusible composite fiber staples; and includes (a) a nonwovenfabric in which fibers are thermally fused at their junctions as the topmaterial, (b) a water absorbing material including pulp and highlyabsorbent resin as the main component, and (c) a polyethylene film asthe bottom material. Only the nonwoven fabric of the diaper in thevicinity of both of the leg-abutting portions were removed by the use ofa knife. The laminated nonwoven fabric obtained in Example 1 waslaminated on the portions in the vicinity of both of the leg-abuttingportions such that the composite meltblown extra-fine-fiber nonwovenfabric layer faced the skin and the composite spun bonded nonwovenfabric layer faced the polyethylene film as the bottom material. Threepolyurethane elastomer threads were disposed between the top materialand the bottom material in a stretched condition. The portions in thevicinity of the center portion of remaining nonwoven fabric and thelaminated nonwoven fabric were thermally fused, and then the bottommaterial described above and the laminated nonwoven fabric werethermally fused. The remaining portion of the laminated nonwoven fabricwas removed by the use of scissors to obtain a disposable diaper inwhich the composite meltblown extra-fine-fiber nonwoven fabric wasarranged to face to the skin of the user's legs. The diaper assumed theshape of an arch due to the elastomer threads placed on the leg-abuttingportions. The diaper had a soft texture at the leg-abutting portions andwas able to prevent liquid from leaking from the same because of thewater-repellency of the meltblown nonwoven fabric. The disposable diaperwas especially suitable for newborn babies.

INDUSTRIAL APPLICABILITY

The laminated nonwoven fabric of the present invention comprises acomposite spun bonded nonwoven fabric laminated on a composite meltblownextra-fine-fiber nonwoven fabric. The laminated nonwoven fabric exhibitsan excellent texture and has an improved strength of nonwoven fabric.Moreover, since fibers are thermally fused to one another at thejunctions thereof in the composite meltblown extra-fine-fiber nonwovenfabric, and the fabric is also thermally fused to the low-melting pointcomponent or the like of a composite spun bonded nonwoven fabric ofcontinuous fiber, the delamination strength is increased and detachmentof fiber is prevented. Further, since no polymer particles are produced,the laminated nonwoven fabric of the present invention provides neitherrough texture nor irritation of skin.

What is claimed is:
 1. A laminated nonwoven fabric of multi-layerstructure comprising a composite spun bonded nonwoven fabric laminatedon a composite meltblown extra-fine-fiber nonwoven fabric having anaverage fiber diameter of 10 μm or less; wherein the composite spunbonded nonwoven fabric comprises a composite continuous fiber composedof a low melting point resin and a high melting point resin, thedifference in melting point between the low melting point resin and thehigh melting point resin being at least 10° C., the low melting pointresin forming at least a portion of the surface of the fiber, and thecomposite spun bonded nonwoven fabric being a thermal fusion product ofthe composite continuous fibers by the mediation of the low meltingpoint resin, the composite meltblown extra-fine-fiber nonwoven fabriccomprises composite meltblown extra-fine fibers composed of a lowmelting point resin and a high melting point resin, the difference inmelting point between the low melting point resin and the high meltingpoint resin being at least 10° C., the low melting point resin formingat least a portion of the surface of the fiber, and the compositemeltblown extra-fine-fiber nonwoven fabric being a thermal fusionproduct of the extra-fine fibers by the mediation of the low meltingpoint resin; and the composite spun bonded nonwoven fabric and thecomposite melt-blown extra-fine-fiber nonwoven fabric are integrated byfusion of the low melting point resin of the composite spun bondednonwoven fabric and/or the low melting point resin of the compositemeltblown extra-fine-fiber nonwoven fabric.
 2. A laminated nonwovenfabric according to claim 1, wherein the composite spun bonded nonwovenfabric comprises composite continuous fibers having a fineness of 0.5-10d/f, the composite meltblown extra-fine-fiber nonwoven fabric comprisesextra-fine fibers having a fiber diameter of 0.1-10 μm, has 10/m² orless of polymer particles having a diameter of at least 0.1 mm, and hasan apparent density of 0.02-0.20 g/cm³; and the laminated nonwovenfabric has a strength in the lateral direction of 0.6 kg/5 cm or more,uniformity index of 0.6 or less, and a delamination strength between thetwo layers of 6 g/5 cm or more.
 3. An absorptive product comprising alaminated nonwoven fabric defined in claim 1 as at least one componentof the product.
 4. An absorptive product according to claim 3, whereinthe product comprises a nonwoven fabric of double-layer structurecomposed of a composite spun bonded nonwoven fabric and a compositemeltblown extra-fine-fiber nonwoven fabric; or a nonwoven fabric ofmulti-layer structure comprising at least three layers, composed of acomposite spun bonded nonwoven fabric and a composite meltblownextra-fine-fiber nonwoven fabric, and having the composite meltblownextra-fine-fiber nonwoven fabric laminated on at least one side of thelaminated nonwoven fabric.
 5. A method of manufacturing a laminatednonwoven fabric comprising the steps of: spinning composite continuousfibers from a low-melting point resin and a high melting point resin sothat at least a portion of the fiber surface is formed by thelow-melting point resin, the difference in melting point between the lowmelting point resin and the high melting point resin being at least 10°C., and forming a spun bonded web by a composite spun bonding method; orheating the resultant fiber web at a temperature not lower than athermal fusion temperature thereby to form a nonwoven fabric in whichthe fibers are thermally fused; spinning composite meltblownextra-fine-fibers having an average fiber diameter of 10 μm or less, andcomprising a low-melting point resin and a high melting point resin, thedifference in melting point between the low melting point resin and thehigh melting point resin is at least 10° C., in such a fashion that thelow-melting point resin forms at least a portion of the fiber surface,and forming a composite extra-fine-fiber web which does not includethermally fused portions by self-heating at the time of spinning, orforming a nonwoven fabric which includes portions thermally fused byself-heating at the time of spinning by a composite melt-blowing method;or forming a composite extra-fine-fiber nonwoven fabric in which thefibers are thermally fused by heating the spun fiber web or the nonwovenfabric which includes thermally self-fused portions at a temperature notlower than a thermal fusion temperature; laminating the spun bonded webor the thermally fused nonwoven fabric, and the composite melt-blownextra-fine-fiber web or a composite melt-blown extra-fine-fiberthermally-fused nonwoven fabric; and heating the resultant laminate at atemperature not lower than the temperature at which the two layersbecome thermally fused.
 6. A method of manufacturing a laminatednonwoven fabric according to claim 5, wherein the method furthercomprises a step of causing entanglement of the fibers in the webs ornonwoven fabrics of the two layers by a needle-punch or spun lace meansbefore or after heating.
 7. A method of manufacturing a laminatednonwoven fabric according to claim 6, wherein the laminate is heatedwith a through-air type heater at least at a thermal fusion temperatureof the two layers.
 8. A method of manufacturing a laminated nonwovenfabric according to claim 5, wherein the two layers are press-bondedunder heating by the use of emboss rolls having a thermal press-bondingarea of 5-25%.
 9. A method of manufacturing a laminated nonwoven fabricaccording to claim 5, wherein the composite spun-bonded nonwoven fabricand the composite melt-blown extra-fine-fiber nonwoven fabric eachhaving a uniformity index of 0.6 or less are used as nonwoven fabric.10. A method of manufacturing a laminated nonwoven fabric according toclaim 5, wherein the two layers are heated with an alternatively hot-airjetting heater such that hot air is jetted from the top face side andthe bottom face side of the nonwoven fabric of multi-layer structure inan alternating manner.
 11. An absorptive product comprising a laminatednonwoven fabric defined in claim 2 as at least one component of theproduct.
 12. A method of manufacturing a laminated nonwoven fabricaccording to claim 6, wherein the two layers are press-bonded underheating by the use of emboss rolls having a thermal press-bonding areaof 5-25%.
 13. A method of manufacturing a laminated nonwoven fabricaccording to claim 6, wherein the composite spun-bonded nonwoven fabricand the composite melt-blown extra-fine-fiber nonwoven fabric eachhaving a uniformity index of 0.6 or less are used as nonwoven fabric.14. A method of manufacturing a laminated nonwoven fabric according toclaim 6, wherein the two layers are heated with an alternatively hot-airjetting heater such that hot air is jetted from the top face side andthe bottom face side of the nonwoven fabric of multi-layer structure inan alternating manner.